Aircraft typically have a cylindrical fuselage supported by horizontal longerons and stringers and by vertical hoop frames. In a commercial aircraft, heavy frame structures are built into the fuselage to provide support for passenger windows. When passenger windows are installed in a commercial aircraft, two acrylic panes typically are installed for each window. An outer, heavier pane is separated by an air gap from an inner, thinner, fail-safe pane. To accommodate the windows and window support structure, sections of every hoop frame intersecting the support structure generally have to be omitted from the fuselage.